Montana Voluntary Manslaughter Law

A homicide occurs anytime one person takes the life of another person, regardless of whether the killing was legal or illegal. In Montana there are five types of criminal homicide: deliberate homicide, mitigated deliberate homicide, negligent homicide, aiding or soliciting suicide, and vehicular homicide while under the influence. This article provides a brief overview of Montana's mitigated deliberate homicide law (referred to as voluntary manslaughter in some states).

Voluntary manslaughter is usually defined as an intentional unlawful killing where the offender had no prior intent to kill, and instead kills in the "heat of passion." These killings would ordinarily be classified as deliberate homicides in Montana; however, the offender is viewed as being less morally culpable because the killing was done in the heat of passion. Therefore, the heat of passion killing is classified as the lesser crime of mitigated deliberate homicide (or voluntary manslaughter). The table below outlines Montana's voluntary manslaughter law.

Code Section

Montana Code section 45-5-103: Mitigated Deliberate Homicide

What's Prohibited?

Purposefully or knowingly causing the death of another human being, or the fetus of another with the knowledge that the woman is pregnant, while under the influence of extreme mental or emotional stress for which there is a reasonable explanation or excuse.

The reasonableness of the explanation or excuse must be determined from the viewpoint of a reasonable person in the offender's situation.

Evidence of Mitigating Circumstances

Mitigating circumstances that reduce the crime of deliberate homicide to mitigated deliberate homicide aren't an element of the reduced crime that the state is required to prove or an affirmative defense that the defendant is required to prove. Neither party has the burden of proof regarding mitigating circumstances, but either party may present evidence of mitigation.


Mitigated deliberate homicide is punishable by imprisonment for a term of between two and 40 years, and/or a fine of up to $50,000, except as provided in section 46-18-219 and section 46-18-222.

Proving "Heat of Passion"

"Heat of passion," referred to as "extreme mental or emotional stress" in Montana, must be shown in order for a killing to be reduced from deliberate homicide to the lesser crime of mitigated deliberate homicide. When an offender acts in the heat of passion, by definition he must have acted without any premeditation. In order to prove that, it must be shown that the provocation was sufficient to drive a reasonable person in the same situation as the offender to lose complete control over themselves. Additionally, it must be shown that the offender acted in the heat of the moment and that there wasn't sufficient time for the offender to cool off before the killing was committed.

Additional Resources

State laws change frequently. For case specific information regarding Montana's voluntary manslaughter law contact a local criminal defense attorney.

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